The control of synthesis and properties of Herpes simplex virus (HSV) specific RNA is being studied. HSV specific mRNA is being localized on the viral genome using RNA displacement loop (R-loop) mapping with the electron microscope. Solution DNA-RNA hybridization techniques are being developed for quantitation of HSV specific RNA and isolation of specific viral mRNA species. Specific fragments of HSV DNA generated by restriction endonuclease cleavage are being used to isolate the viral RNA species they encode. The properties and possible processing of viral RNA will be studied by use of these hybridization techniques and high resolution denaturing acrylamide gel electrophoresis. HSV RNA synthesis in cells which support only restricted viral growth will be studied. Finally, HSV RNA synthesis will be studied in vitro using isolated nuclei and nuclear fractionation techniques.